Field of the Invention
This invention relates to the manufacture of packaged semiconductor devices or modules. More particularly, this invention relates to the manufacture of hybrid semiconductor packages which include a plurality of individual semiconductor devices bonded to a substrate in a manner which facilitates their non-destructive removal.
Heretofore, semiconductor devices have been made with common anodes or common cathode connections at the base. The individual chips or semiconductor devices have been connected to various types of circuit patterns by solder reflow bonding, soldering, conductive adhesives, wire bonding and by utectic bonding.
It is well known that integrated circuits (I.C.) semiconductor devices may be made having a very large number of active components on a single device. Such devices are being made with several thousand individual active elements on a single chip. The price of an individual component is substantially reduced, the speed of switching is usually increased and the power consumption of the device is usually reduced. Accompanying these desirable features have been lower yields of devices per wafer, increase testing costs and more elaborate processing techniques.
In the data processing equipment industry it has been desirable to mount individual integrated circuit chips in a separate package such as dual in-line pin (DIP) package which enable the package containing the device to be easily mounted by insertion on a printed circuit board. The pins on the IC package and leads from other components on the board may be made permanent by solder wave connecting the pins and leads to a printed circuit board. The removal of a faulty integrated circuit from a fiberglass epoxy printed circuit board is implemented by removing the individual pins or leads on the package from the printed circuit. This enables a new package or device to be inserted in the old connection holes on the printed circuit board when making a repair.
In the data processing equipment industry it has become desirable to reduce the size of printed circuit boards or modules which contain a plurality of the aforementioned integrated circuit packages. The size of the packages containing the individual IC chips cannot be easily reduced and it is desirable to mount the unpackaged integrated circuit on a printed circuit board or substrate to further reduce the size of the module.
Heretofore, a plurality of individual small scale integrated circuits have been mounted on a ceramic substrate and wire bonded to a circuit pattern on the substrate to provide hybrid integrated circuits. Integrated circuits having a larger number of devices have been connected to pads or targets on such substrates at a common base anode or cathode connection by conventional bonding methods. When the large scale integrated circuit devices are found to be faulty and must be removed from the substrate in order to replace the faulty device, the IC device has usually been destroyed during the process of removal and in some instances part of the printed circuit on the substrate has been destroyed. Often when heat is applied to the top of the integrated circuit to remove the faulty device, the heat also destroys adjacent integrated circuit devices which were not faulty before an attempt to remove the faulty device. Excess heat applied to the device and the adjacent printed circuit pattern may cause either the pattern or the adjacent devices to become unusable.
Some microelectronic module packages are too expensive to be thrown away if only a small part of a hybrid integrated circuit fails. Accordingly, it is desirable to be able to open individual packages or modules and replace the defective devices without affecting the printed circuit pattern or adjacent semiconductor devices. It is also desirable to be able to replace a new component in a package which is substantially complete without incurring large repair costs.